Telephone technology provides users of the phone with a readily available means of communicating over long distances. A typical telephone or other audio communication device provides a microphone that the user speaks into, a communication link between the user and another party, and a speaker that provides the other party's voice to the user. Over time, audio communication technology has come to include mobile phones, such as cellular phones, satellite phones, and other devices.
Noise cancellation techniques exist to reduce unwanted noise that may interfere with audio communication, such as unwanted noise that interferes with a user listening to another party on a telephone or a headset device. Active noise reduction (ANR) techniques provide a sound wave that is out of phase with the unwanted noise. For example, in an airplane, an ANR technique provides an antinoise sound wave designed to mask or greatly reduce the noise of jet engines so that pilots or passengers in the airplane may use headsets in the airplane without distraction. The ANR technique includes using a microphone to detect a sound, such as the jet engine, electronic circuitry to produce an antinoise sound wave opposite in phase to the noise, and a speaker to broadcast the antinoise sound wave into or near a user's ear, such as through a headset that the user is wearing or from a location near the user's ear. The antinoise sound wave destructively interferes with the noise. The result is the reduction of the noise to a more comfortable level for the user.